Instruments and methods for minimally invasive tissue retraction and surgery

ABSTRACT

Methods and devices retract tissue for minimally invasive surgery in a patient. A retractor includes a working channel formed by a first portion and a second portion. The first and second portions are movable relative to one another from a first configuration for insertion that minimizes trauma to skin and tissue to an enlarged configuration after insertion to further retract skin and tissue in a minimally invasive manner. Instruments are engageable to the first and second portions and operable to move the first and second portions relative to one another.

CROSS-REFERENCE TO RELATES APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/180,658 filed on Jun. 26, 2002, and now issued as U.S. Pat. No.6,945,933, which is incorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to instruments and methods for performingtissue retraction and surgeries through the retracted tissue inminimally invasive procedures.

Traditional surgical procedures for pathologies located within the bodycan cause significant trauma to the intervening tissues. Theseprocedures often require a long incision, extensive muscle stripping,prolonged retraction of tissues, denervation and devascularization oftissue. These procedures can require operating room time of severalhours and several weeks of post-operative recovery time due to thedestruction of tissue during the surgical procedure. In some cases,these invasive procedures lead to permanent scarring and pain that canbe more severe than the pain leading to the surgical intervention.

The development of percutaneous procedures has yielded a majorimprovement in reducing recovery time and post-operative pain becauseminimal dissection of tissue, such as muscle tissue, is required. Forexample, minimally invasive surgical techniques are desirable for spinaland neurosurgical applications because of the need for access tolocations within the body and the danger of damage to vital interveningtissues. While developments in minimally invasive surgery are steps inthe right direction, there remains a need for further development inminimally invasive surgical instruments and methods.

SUMMARY

The present invention is directed to methods and instruments forperforming surgery in a patient. One specific application concernsinstruments and methods for tissue retraction in minimally invasivespinal surgery. A further specific application includes instruments forpercutaneous tissue retraction to provide access to a surgical locationin the patient. Another specific application includes surgical methodsperformed through the percutaneously retracted tissue at any location ina patient's body. Other applications of the invention will also beapparent from the following description of the illustrated embodiments.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of one embodiment retractor in an insertionconfiguration.

FIG. 2 is a perspective view of the retractor of FIG. 1 with first andsecond portions of the retractor separated from one another.

FIG. 3 is a perspective of another embodiment retractor in an insertionconfiguration.

FIG. 4 is a detailed view of one configuration of adjacent retractorportions in an insertion configuration.

FIG. 5 is a detailed view of another configuration of adjacent retractorportions in an insertion configuration.

FIG. 6 is a detailed view of another configuration of adjacent retractorportions in an insertion configuration.

FIG. 7 is a plan view of the retractor of FIG. 1 in an insertionconfiguration with an instrument for separating first and secondportions of the retractor coupled thereto.

FIG. 8 is a section view through line 8-8 of FIG. 7 in which theretractor has been inserted over sequential tissue dilators.

FIG. 9 is the retractor of FIG. 8 with the working channel of theretractor enlarged.

FIG. 10 is a side view of another embodiment retractor in an insertionconfiguration.

FIG. 11 is the retractor of FIG. 10 with the working channel enlarged.

FIG. 12 is a perspective view of another embodiment retractor andinstrument for separating first and second portions of the retractor.

FIG. 13 is a perspective view of another embodiment retractor andinstrument for separating first and second portions of the retractor.

FIG. 14 is a perspective view of another embodiment retractor andinstrument for separating first and second portions of the retractor.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any such alterations and furthermodifications in the illustrated devices and described methods, and anysuch further applications of the principles of the invention asillustrated herein are contemplated as would normally occur to oneskilled in the art to which the invention relates.

The present invention provides instruments and methods for performingpercutaneous surgery, including spinal surgeries that include one ormore techniques such as laminotomy, laminectomy, foramenotomy,facetectomy, discectomy, interbody fusion, spinal nucleus or discreplacement, and implant insertion, for example. The surgery isperformed through a working channel or passageway through skin andtissue of the patient provided by a retractor. Viewing of the surgicalsite at the working end of the retractor can be accomplished withviewing instruments mounted on the retractor, positioned over theretractor, and/or through a viewing system such as lateral fluoroscopy.The retractor is movable in situ to increase the size of the workingchannel to facilitate access to the working space at the distal end ofthe retractor while minimizing trauma to tissue surrounding theretractor. The retractor can be used with any surgical approach to thespine, including anterior, posterior, posterior mid-line, lateral,postero-lateral, and/or antero-lateral approaches, and in other regionsbesides the spine.

In FIG. 1 there is illustrated a retractor 20 that includes a firstportion 22 and a second portion 42. First portion 22 has a distal end 24and an opposite proximal end 26. Second portion 42 has a distal end 44and an opposite proximal end 46. Distal ends 24, 44 can be beveled tofacilitate insertion, although non-beveled ends are also contemplated.First portion 22 can be positioned adjacent to or mated with secondportion 42 along adjacent ones of the longitudinal edges 25 of firstportion 22 and longitudinal edges 45 of second portion 42. A workingchannel 50 is formed between first portion 22 and second portion 42.Working channel 50 extends between and opens at distal ends 24, 44 andproximal ends 26, 46.

Retractor 20 is insertable through skin and tissue of a patient toprovide working channel 50 to the surgical site. It is contemplated thatretractor 20 is inserted through the skin and tissue in an insertionconfiguration for working channel 50, such as shown in FIG. 1. In theinsertion configuration, working channel 50 is substantially enclosed orcircumscribed by first portion 22 and second portion 42. After insertioninto the patient, working channel 50 can be enlarged by separating firstportion 22 and second portion 42. Separation of first and secondportions 22, 42 increases the size of working channel 50 from proximalends 26, 46 to distal ends 24, 44.

In the insertion configuration of FIG. 1, working channel 50 iscircumscribed or substantially enclosed by first portion 22 and secondportion 42. Working channel 50 can have a size in the insertionconfiguration that allows passage of one or more surgical instrumentsand/or implants to the surgical location in the patient's body. It maybe desirable during surgery to provide greater access to the location inthe patient's body beyond the locations provided through working channel50 in its insertion configuration. First portion 22 and second portion42 are movable away from one another to enlarge working channel 50. Inthe enlarged configuration of working channel 50, a space is formedbetween at least of the adjacent longitudinal edges 25, 45 of first andsecond portions 22, 42. The space between the adjacent longitudinaledges 25, 45 exposes enlarged working channel 50 to skin and tissue ofthe patient between the separated first portion 22 and second portion42. This exposed tissue can also be accessed by the surgeon through theenlarged working channel 50 with one or more instruments and/orimplants. It is further contemplated that a shield, guard or tissueretractor could be placed in enlarged working channel 50 to maintain theexposed tissue away from the enlarged working channel 50.

First portion 22 includes a semi-cylindrical body 23 extending betweendistal end 24 and proximal end 26. A collar 28 extends about proximalend 26, and forms a lip extending about the outer surface of body 23.First portion 22 includes a first bracket member 39 extending fromproximal end 26. Second portion 42 includes a semi-cylindrical body 43extending between distal end 44 and proximal end 46. A collar 48 extendsabout proximal end 46 of second portion 42, and defines a lip extendingabout the outer surface of body 43. Second portion 42 includes a secondbracket member 40 extending from proximal end 46.

A first alignment member 30 can be provided to couple a first side offirst portion 22 to second portion 42 adjacent proximal ends 26, 46. Asecond alignment member 31 opposite first alignment member 30 can beprovided to couple the other side of first portion 22 to second portion42 adjacent proximal ends 26, 46 along another side of retractor 20.Holding member 38 can be positioned about bracket members 39, 40 to holdfirst portion 22 and second portion 42 adjacent one another. In oneembodiment, alignment members 30, 31 are pins slidably received in holes43 (only one shown in FIG. 2) formed in the other retractor portion whenretractor 20 is in its insertion configuration. Alignment members 30, 31maintain first portion 22 and second portion 42 in longitudinalalignment with one another during and after insertion. Holding member 38can be resiliently biased to engage bracket members 39, 40 and maintainfirst portion 22 and second portion 42 adjacent one another during andafter insertion. Holding member 38 can be removed from bracket members39, 40 when it is desired to separate first and second portions 22, 42.

Other arrangements are also contemplated for aligning and releasablycoupling first portion 22 and second portion 42 to one another. Examplesof such arrangements include dovetail connections, fasteners, threadedcoupling members, clamping members, snap rings, compression bands,straps, ball-detent mechanisms, and releasably interlocking cams ortabs, for example. Examples of suitable holding members include clamps,clips, bands, straps, hooks, ties, sleeves, coupling members and/orfasteners. As shown in FIG. 3, holding member 38 can be provided with aclamping mechanism 35 to bias holding member 38 into engagement withbracket members 39, 40. Clamping mechanism 35 can include a thumb wheeland threaded shaft that bears against one or both of the bracket members39, 40 to solidly attach holding member 38 thereto and provide a quickdisconnect of holding member 38 from bracket members 39, 40.

Bracket member 39 and 40 can extend from and be integrally formed withor attached to respective ones of the collars 28, 48 of first and secondportions 22, 42. Bracket members 39, 40 can also be provided as a singlebracket on one of the collars 28, 48 in lieu of or in addition tobracket members 39, 40. Bracket members 39, 40 extend away from workingchannel 50 and are connectable to one end of a flexible or articulatablearm 41 (FIG. 7.) The opposite end of arm 41 (not shown) can be mountedon the surgical table or other support device. Arm 41 supports retractor20 in the patient yet allows percutaneous manipulation andre-positioning of retractor 20 during surgery. It is furthercontemplated that more than one flexible arm 41 can be provided toengage respective ones of the retractor portions 22, 42 afterenlargement of working channel 50.

With working channel 50 of retractor 20 in its insertion configuration,the opposite edges 25 of first portion 22 are adjacent respective onesof the opposite edges 45 of second portion 42. Various interfacesbetween the edges 25, 45 are contemplated. For example, in FIG. 4 thereis shown a configuration in which edges 25 (only one shown) of firstportion 22 abut along all or a portion of the adjacent edge 45 of secondportion 42 in the insertion configuration for working channel 50. InFIG. 5 there is another embodiment first portion 22 having an outerrecess 27 along each of the edges 25 (only one shown.) Each of the edges45 can include an inner recess 47. Edges 25, 45 can thus interdigitateand abut one another in recesses 27, 47 in the insertion configurationfor working channel 50. In FIG. 6 there is shown an overlappingarrangement in which edges 25 (only one shown) of first portion 22 canbe located inside, relative to working channel 50, the adjacent edge 45of second portion 42. It is also contemplated that edge 45 could belocated inside edge 25. It is further contemplated that on one side ofretractor 20 edge 25 can be inside edge 45, and on the other side ofretractor 20 the other edge 45 can be inside the other edge 25. Otherarrangements contemplate a gap between adjacent ones of the edges 25,45.

Body 23 has a perimeter length along distal end 24 which can be aboutthe same as the perimeter length of body 23 at proximal end 26. Body 43of second portion 42 includes a perimeter length along distal end 44which can be about the same as the perimeter length of body 43 adjacentproximal end 46. Bodies 23, 43 can have a semi-circular cross-section,and form a generally circular cross-section for working channel whenplaced adjacent one another, as shown in FIG. 1. Other cross-sectionalshapes are also contemplated for first and second portions 22, 42, suchas, for example, any open sided polygonal shape, curved shape, orcombined curved/polygonal shape.

Extending proximally from collar 28 of first portion 22 is a firstengagement member 32 having a head portion 36 forming a recess 33therebelow. Extending proximally from collar 48 of second portion 42 isa second engagement member 52 having a head portion 56 forming a recess53 therebelow. Head portions 36, 56 can be threadingly engaged,reciprocally engaged and spring biased toward collars 28, 48, orotherwise engaged to the respective collar 28, 48 and adjustable toincrease and decrease the height of the respective recess 33, 53 toreceive and couple a separation instrument therein. It is alsocontemplated that engagement members 32, 52 can be non-adjustable, andthe separation instrument configured to engage the adjacent engagementmember 32, 52.

As discussed further below, an instrument for separating first portion22 and second portion 42 can be non-releasably or releasably engaged toengagement members 32, 52 for application of a separation force toenlarge working channel 50 by separating first portion 22 and secondportion 42. Such an instrument could also be releasable ornon-releasably engaged to first portion 22 and second portion 42. Suchan instrument could also maintain first portion 22 and second portion 42in the initial insertion configuration and/or in the enlargedconfiguration for working channel 50. Other means besides the separationinstrument could also be employed for maintaining first portion 22 andsecond portion 42 in one or both of the initial insertion configurationand the enlarged configuration for working channel 50. For example, whenthe separation instrument is not attached, a member could extend betweenand be coupled to each of the engagement members 32, 52 and/or retractorportions 22, 42.

Engagement members 32, 52 are positioned on lateral extensions 29, 49 ofcollars 28, 48, respectively. Lateral extensions 29, 49 extend farenough laterally to allow engagement of a separation instrument toengagement members 32, 52 without obstructing working channel 50 withthe separation instrument.

It is contemplated that body 23 can be provided with a thickness 39(FIG. 4.) Body 43 of second portion 42 can be provided with a thickness59 (FIG. 4) that can be the same, greater than, or less than thickness39 of first portion 22. Bodies 23, 43 can be provided with sufficientrigidity between their distal and proximal ends to separate and maintainseparation of body tissue when retractor is initially inserted and alsowhen tissue is retracted by moving first portion 22 and second portion42 away from one another. First thickness 39 and second thickness 59 canprovide first portion 22 and second portion 42, respectively, withsufficient rigidity to resist bending or bowing under the forces exertedon it by the retracted tissue. Also, body 23 has a depth 37 from edges25 to the midpoint of wall of body 23 extending between edges 25. Depth37 can provide a sufficient section modulus or moment of inertia in thedirection of movement of first portion 22 to resist bending, bowingand/or deflection forces applied during such movement. Similarly, body43 can have a depth 57 from edges 45 to the midpoint of wall of body 43extending between edges 45 to provide a sufficient section modulus ormoment of inertia in the direction of movement of second portion 42 toresist bending, bowing, and/or deflection forces applied during suchmovement.

In one specific embodiment, first portion 22 and second portion 42 areeach made from surgical grade stainless steel. Other materials are alsocontemplated for first and second portions 22, 42, including, forexample, plastics and metals and metal alloys, such as, for example,spring steel, shape memory metals and alloys, and aluminum.

In the initial insertion configuration, working channel 50 has agenerally circular cross-section along retractor 20, as shown in FIGS.1, 7 and 8. Working channel 50 has a first width 51 in the direction ofmovement of first portion 22 relative to second portion 42, and a secondwidth 55 extending from one of the pair of adjacent edges 25, 45 to theother of the pair of adjacent edges 25, 45. In the illustratedembodiment, first and second widths 51 and 55 can be substantially thesame since working channel 50 has a generally circular cross-section inits initial insertion configuration. In the enlarged configuration, asshown in FIGS. 2 and 9, second width 55 remains generally the same as inthe initial insertion configuration for retractor 20, while first width51 is increased by separating first portion 22 and second portion 42.

Various configurations for working channel 50 are contemplated. In theinitial insertion configuration, working channel 50 can have acylindrical shape with, for example, a circular, oval, elliptical,polygonal, or combined polygonal/curved cross-sectional shape. In theenlarged configuration, working channel 50 can have a cylindrical orfrusto-conical shape with, for example a cross-section that is oval,elliptical, circular, curved, polygonal, or combined polygonal/curved inshape.

One specific application for retractor 20 is in spinal surgery. It iscontemplated that, after insertion of retractor 20, first portion 22 andsecond portion 42 are separated predominantly in one direction toretract muscle and tissue along pathway 62 (FIG. 7.) For example, firstand second portions 22, 42 of retractor 20 can be primarily orpredominantly separable in the direction of the spinal column axis. Themuscle tissue adjacent the spine has a fiber orientation that extendsgenerally in the direction of the spinal column axis. The separation ofbody portions 23, 43 of retractor 20 separates the muscle tissue alongthe fibers, thus the amount of separation and the resultant tearing andtrauma to the muscle tissue can be minimized. It is also contemplated inother techniques employing retractor 20 that working channel 50 can beenlarged primarily in a direction other than along the spinal columnaxis or in areas other than spine. Embodiments of retractor 20 are alsocontemplated in which working channel 50 is enlarged substantially inone direction or in all directions.

Referring now to FIGS. 7-9, one example of a method for positioning ofretractor 20 through the skin 60 and tissue 68 of the patient will bedescribed. An incision is made in skin 60 adjacent the location of apatient's anatomy to be accessed. For example, in spinal surgery, theincision can be made at a vertebral level at a location that providesaccess to the disc space between adjacent vertebrae or to one or morevertebra through a desired approach. Prior to insertion of retractor 20,skin 60 and tissue 68 can be sequentially dilated via dilationinstrument set 66 which can include guidewires and/or one or more tissuedilators of increasing size. The tissue dilators are inserted one overanother to form a pathway 62 through skin 60 and tissue 68 to thesurgical site in the patient. In such procedures, retractor 20 ispositioned over the last inserted dilator to form pathway 62 in the skinand tissue. Working channel 50 through retractor 20 provides access to aworking space 64 at the distal end of retractor 20 when the guidewiresand dilators, if used, are removed therefrom.

For the entire surgery or for certain procedures during the surgery, itmay be desired by the surgeon to increase the size of working channel 50to facilitate access working space 64 below the distal end of retractor20, or to increase the size of working space 64. First and secondportions 22, 42 of retractor 20 can be separated from their insertionconfiguration to a separated configuration in which working channel 50is enlarged, as shown in FIG. 9. In the enlarged configuration, firstportion 22 and second portion 42 can be moved laterally and/or pivotedaway from one another by a separation instrument. One example of aseparation instrument is separation instrument 70 extending between andcoupled to engagement members 32, 52. Adjacent ones of the edges 25, 45are separated by a space 69, exposing working channel 50 to the skin andtissue along pathway 62 while first and second portions 22, 42 holdtissue out of the operative field. In the enlarged configuration,working channel 50 and thus pathway 62 are enlarged through the throughskin 60 and tissue 68 formed by first portion 22 and second portion 42.The size of working space 64 can be increased while minimizing trauma tothe tissue and skin along pathway 62.

First and second portions 22, 42 can be pivoted or rotated away from oneanother about their proximal ends to provide working channel 50 with atapered configuration that reduces in size from the distal end ofretractor 20 adjacent working space 64 through skin 60 to the proximalend of retractor 20. A tapered working channel provides the surgeongreater access and increased visualization of working space 64 whileminimizing tissue retraction. The tapered working channel 50 also allowsgreater angulation of instruments placed through working channel 50,more selection in positioning of instruments within working channel 50,and the ability to position instruments adjacent the inner wall surfacesof the separated first and second portions 22, 42, increasing the roomavailable at working space 64 for multiple instruments.

Viewing instruments can be positioned in or adjacent to working channel50 to facilitate surgeon viewing of working space 64 and the operativesite. For example, an endoscopic viewing element can be mounted on theproximal end of retractor 20 with a scope portion extending alongworking channel 50. A microscopic viewing element can be positioned overthe proximal end of retractor 20 for viewing working space 64 and thesurgical site. Other imaging techniques, such as lateral fluoroscopy,can be used alone or in combination with the endoscopic and microscopicviewing elements. It is further contemplated that other instruments canbe mounted on the proximal end of retractor 20, such as nerve rootretractors, tissue retractors, forceps, cutter, drills, scrapers,reamers, separators, rongeurs, taps, cauterization instruments,irrigation and/or aspiration instruments, illumination instruments andthe like for use in surgical procedures through retractor 20 in theworking space. Such viewing instruments and other instruments can beemployed with working channel 50 in its initial insertion configurationand/or its enlarged configuration.

Referring now to FIG. 7, further details regarding one embodimentinstrument 70 for separating first and second portions 22, 42 will beprovided. Instrument 70 includes a rack portion 72 and a body portion74. Rack portion 72 includes a foot portion 76 releasably engageable toengagement member 52, and body portion 74 includes a foot portion 78releasably engageable to engagement member 32. Rack portion 72 includesan extension 80 received through a housing 82 of body portion 74.Housing 82 includes a pinion 84 rotatably mounted therein and engagedwith teeth 86 of extension 80. Pinion 84 can be engaged by a tool ormanually by the surgeon and rotated to move rack portion 72 relative tobody portion 74, thereby moving feet portion 76, 78 away from oneanother to separate first portion 22 and second portion 42 to enlargeworking channel 50. A stop member 88 can be provided at the end of or atany position along extension 80 to prevent over-separation of firstportion 22 and second portion 42.

Referring now to FIGS. 10 and 11, another embodiment retractor 20 isshown in which retractor portions 22, 42 are simultaneously separablefrom one another and pivotal relative to one another to enlarge workingchannel 50. Collar 28 includes an extension 300 extending from body 23of first portion 22 generally in the direction of separation of firstportion 22 from second portion 42. Collar 48 includes an extension 302extending from body 43 of second portion 42 generally in the directionof separation of second portion 42 from first portion 22. In theinsertion configuration of FIG. 10, extension 300 extends distally fromcollar 28 at an angle 304, and extension 302 extends distally fromcollar 48 at an angle 306. Engagement members 32, 52 extend proximallyfrom respective ones of the extensions 300, 302.

In FIG. 11, working channel 50 has been enlarged by application of alateral separation force with, for example, separation instrument 70discussed above or instrument 220 discussed below, as indicated byarrows 312, 314. The lateral separation forces move first portion 22away from second portion 42. The lateral separation forces are appliedto the engagement members 32, 52 on the angled extensions 300, 302.Angled extensions 300, 302 tend to cause distal ends 24, 44 to pivot orrotate away from one another as angled extensions 300, 302 are rotatedor pivoted in the direction in which lateral forces 314, 316 areapplied. As a result, edges 25, 45 form angle 307 therebetween andprovide working channel 50 with an enlarged, frusto-elliptical shapebetween the distal ends 24, 44 and proximal ends 26, 46. Distal ends 24,44 are separated at edges 25, 45 by a distance 308, which is greaterthan the distance 310 separating edges 25, 45 adjacent proximal ends 26,46.

Referring now to FIG. 12, there is shown retractor 20 with anotherembodiment instrument 90 for separating first portion 22 and secondportion 42. Instrument 90 includes a rotational separator 92 and alateral separator 110. Rotational separator 92 is operable to rotate orpivot first portion 22 and second portion 42 relative to one anotherabout their proximal ends 26, 46 to move distal ends 24, 44 away fromone another. Lateral separator 110 is operable to move first portion 22and second portion 24 away from one another by separating proximal ends26, 46 and distal ends 24, 44 laterally. As discussed further below,instrument 90 can be coupled to engagement members (not shown) of thefirst and second portions 22, 42 located adjacent one of the edges 25,45 and extending laterally from the respective first and second portions22, 42. Rotational separator 92 and lateral separator 110 can beoperated sequentially to pivot then laterally separate, or laterallyseparate and then pivot first and second portions 22, 42. Rotationalseparator 92 and lateral separator 110 can also be operatedsimultaneously to pivot/rotate and laterally separate first and secondportions 22, 42.

Rotational separator 92 includes a first handle 94 and a second handle96. First handle 94 is mounted to a first coupling member 98, and secondhandle 96 is mounted to a second coupling member 100. First couplingmember 98 of rotational separator 92 is non-rotatably coupled to thelateral engagement member of first portion 22, and second couplingmember 100 of rotational separator 92 is non-rotatably coupled to thelateral engagement member of second portion 42. First and secondportions 22, 42 are pivotal or rotatable away from one another by movingfirst handle 94 in the direction of arrow 105 toward second handle 96,and by moving second handle 96 in the direction of arrow 106 towardfirst handle 94. Movement of handles 94, 96 in the direction of arrows105, 106 rotates the proximal ends of coupling members 98, 100 towardone another to effect the pivotal or rotational movement of first andsecond portions 22, 42. Handles 94, 96 can be pivotally coupled toconnectors 98, 100 for rotation in the direction of arrow 108 to movehandles 94, 96 away from the proximal end opening of working channel 50and provide the surgeon clear access thereto.

Lateral separator 110 extends laterally from retractor 20 transverselyto the direction of separation of first portion 22 and second portion42. Lateral separator 110 includes a first handle 112 and a secondhandle 114. A first coupling member 116 is pivotally coupled at amid-portion thereof to first handle 112, and a second coupling member118 is pivotally coupled at a mid-portion thereof to second handle 114.Coupling members 116, 118 are rotationally coupled at their distal endsto respective ones of the lateral engagement members extending fromfirst portion 22 and second portion 42. A first link 120 extends betweenand is pivotally coupled at one end to first handle 112 and at itsopposite end to second coupling member 118. A second link 122 extendsbetween and is pivotally coupled at one end to second handle 114 and atits opposite end to first coupling member 116. First coupling member 116includes a first tab 134 that rotatably receives the lateral engagementmember extending from first portion 22. Second coupling member 118includes a second tab 136 that rotatably receives the lateral engagementmember extending from second portion 42.

First link 120 includes a first slot 124, and second link 122 includes asecond slot 126. A locking pin 128 extends through slots 124, 126 andcouples links 120, 122 to one another. To laterally separate firstportion 22 from second portion 42, locking pin 128 is loosened so thelinks 120, 122 are movable relative to one another. First handle 112 ismoved in the direction of arrow 130 toward second handle 114, and secondhandle 114 is moved in the direction of arrow 132 toward first handle112. First link 120 pushes outwardly on second coupling member 118 whilesecond handle 114 pulls outwardly on second coupling member 118.Similarly, second link 122 pushes outwardly on first coupling member 116while first handle 112 pulls outwardly on first coupling member 116.Coupling members 116, 118 thus laterally move away from one another.This separates first and second portions 22, 42 such that edges 25, 45are displaced laterally the same relative distance from one anotherbetween proximal ends 26, 46 and distal ends 24, 44. Locking pin 128 canthen be threaded to clamp link members 120, 122 together and preventfurther movement of lateral separator 110. Movement of handles 112, 114in the direction opposite arrows 130, 132 moves first and second portion22, 42 toward one another, and, if pivoted, movement of handles 94, 96toward one another can pivot first and second portions 22, 42 toward oneanother to reduce working channel 50 for easier removal of retractor 20from the incision.

First and second adjustment mechanisms 102, 104 are provided for smallincremental adjustment in the rotational positioning of first portion 22and second portion 42, respectively. First adjustment mechanism 102extends through first tab 134 and engages first coupling member 98. Asfirst adjustment mechanism 102 is threaded toward first tab 134, the endof first adjustment mechanism 102 pushes on first coupling member 98,causing first coupling member 98 and first handle 94 along with firstportion 22 to pivot or rotate relative first tab 134. Adjustmentmechanism 102 can also engage first coupling member 98 to maintain firstportion 22 in a pivoted or rotated position provided through firsthandle 94. Similarly, second adjustment mechanism 104 extends throughsecond tab 136 and engages second coupling member 100. As secondadjustment mechanism 104 is threaded toward second tab 136, the end ofsecond adjustment mechanism 104 pushes on second coupling member 100,causing second coupling member 100 and second handle 96 along withsecond portion 42 to pivot or rotate relative second tab 136. Secondadjustment mechanism 104 can also engage second coupling member 100 andmaintain second portion 42 in a pivoted or rotated position providedthrough second handle 96.

In use, the resistance to retraction provided by the tissue may preventdistal ends 24, 44 from separating as far as proximal ends 26, 46 when aseparation force is applied with lateral separator 110. Rotationalseparator 92 can be used to move distal ends 24, 44 away from oneanother to provide the desired separation between edges 25, 45 along thelength of first and second portions 22, 42.

Referring now to FIG. 13, there is shown retractor 20 with anotherembodiment instrument 140 for separating first portion 22 and secondportion 42. Instrument 140 includes a rotational separator 142 and alateral separator 160. Rotational separator 142 is operable to rotate orpivot first portion 22 and second portion 42 relative to one anotherabout their proximal ends 26, 46 to move distal ends 24, 44 away fromone another. Lateral separator 160 is operable to move first portion 22and second portion 24 away from one another by separating proximal ends26, 46 and distal ends 24, 44 laterally. Rotational separator 142 andlateral separator 160 can be operated sequentially to pivot thenlaterally separate, or laterally separate and then pivot first andsecond portions 22, 42. Rotational separator 142 and lateral separator160 can also be operated simultaneously to pivot/rotate and laterallyseparate first and second portions 22, 42.

Rotational separator 142 includes a first handle 144 and a second handle146. First handle 144 has a first coupling member 148, and second handle146 has a second coupling member 150. First coupling member 148 includesa slot 149 to receive engagement member 32 of first portion 22, andsecond coupling member 150 includes a slot 151 to receive engagementmember 52 of second portion 42. First and second portions 22, 42 arepivotal or rotatable away from one another by moving first handle 144 inthe direction of arrow 155 toward second handle 146, and by movingsecond handle 146 in the direction of arrow 156 toward first handle 144.Movement of handles 144, 146 in the direction of arrows 155, 156 movescoupling members 148, 150 away from one another to effect the pivotal orrotational movement of first and second portions 22, 42 relative to oneanother.

Lateral separator 160 includes a first handle 162 and a second handle164. A first connector 166 is pivotally coupled at a mid-portion thereofto first handle 162, and a second connector 168 is pivotally coupled ata mid-portion thereof to second handle 164. Connectors 166, 168 arepivotally coupled at their distal ends to respective ones of firsthandle 144 and second handle 146 of rotational separator 142.

A first link 170 extends between and is pivotally coupled at one end tofirst handle 162 and at its opposite end to second connector 168. Asecond link 172 extends between and is pivotally coupled at one end tosecond handle 164 and at its opposite end to first connector 166. Firstconnector 166 includes a first locking member 152 pivotally coupledthereto that can extend through and releasably engage first handle 144.Second connector 168 includes a second locking member 154 pivotallycoupled thereto that can extend through and releasably engage secondhandle 146. Locking members 152, 154 can selectively engage and maintainthe positioning of handles 142, 144 at any one of a number of positionsto which first portion 22 and second portion 42 have been rotated orpivoted by rotational separator 142.

First link 170 includes a first slot 174, and second link 172 includes asecond slot 176. A locking pin 178 extends through slots 174, 176 andcouples links 170, 172 to one another. To laterally separate firstportion 22 from second portion 42, locking pin 178 is loosened so links170, 172 are movable relative to one another. First handle 162 is movedin the direction of arrow 180 toward second handle 164, and secondhandle 164 is moved in the direction of arrow 182 toward first handle162. First link 170 pushes outwardly on second coupling member 168 whilesecond handle 164 pulls outwardly on second coupling member 168.Similarly, second link 172 pushes outwardly on first coupling member 166while first handle 162 pulls outwardly on first coupling member 166.Coupling members 166, 168 laterally move connecting portions 148 awayfrom one another. Thus, actuation of handles 162, 164 laterallyseparates the connected first and second portions 22, 42 such that edges25, 45 are laterally displaced relative to one another between proximalends 26, 46 and distal ends 24, 44. Locking pin 178 can then be threadedto clamp link members 170, 172 together and prevent further movement oflateral separator 160. Movement of handles 162, 164 in the directionopposite arrows 180, 182 moves first and second portion 22, 42 towardone another to reduce the spacing therebetween for easier removal ofretractor 20 from the incision.

In use, the resistance to retraction provided by the tissue may preventdistal ends 24, 44 from separating as far as proximal ends 26, 46 when aseparation force is applied with lateral separator 160. Rotationalseparator 142 can be used to move distal ends 24, 44 away from oneanother to provide the desired separation between edges 25, 45 along thelength of first and second portions 22, 42.

Instrument 140 is positioned over the proximal end opening of workingchannel 50. To provide clear access to working channel 50 for thesurgeon, instrument 140 can be removed from retractor 20, and a guidemechanism 190 can maintain the lateral and rotational positioning offirst portion 22 and second portion 42 obtained with instrument 140.Guide mechanism 190 includes a guide member 200 having a slot 202 formedtherein. Guide member 200 extends between first portion 22 and secondportion 42 along one side thereof, and first and second portions 22, 42are coupled thereto. It is also contemplated that a second guide membercould be provided on the other side of retractor 20.

A first coupling member 192 is movably mounted in slot 202 of guidemember 200 adjacent first portion 22, and a second coupling member 214is movably mounted in slot 202 of guide member 200 adjacent secondportion 42. First portion 22 includes a first ear 208 extending fromcollar 28 pivotally coupled at one end 194 of first coupling member 192.At the other end of first coupling member 192 is a cam locking mechanism196 that is releasably engageable to guide member 200 to maintain thepositioning of first portion 22 along guide member 200. Second portion42 includes a second ear 210 extending from collar 48 that is pivotallycoupled at one end 212 of second coupling member 214. At the other endof second coupling member 214 is a cam locking mechanism 216 that isreleasably engageable to guide member 200 to maintain the positioning ofsecond portion 42 along guide member 200.

First and second adjustment mechanisms 198, 206 are provided for smallincremental adjustment in the rotational positioning of first portion 22and second portion 42, respectively. First adjustment mechanism 198extends through first ear 208 and engages first coupling member 192. Asfirst adjustment mechanism 198 is threaded toward first ear 208, the endof first adjustment mechanism 198 engages first coupling member 192,maintaining first portion 22 in its pivoted position relative to guidemember 200. First adjustment mechanism 198 can also be manipulated bythe surgeon for small adjustments in the pivotal position of firstportion 22 relative to guide member 200 and second portion 42. Secondadjustment mechanism 206 extends through second ear 210 and engagessecond coupling member 214. As second adjustment mechanism 206 isthreaded toward second ear 210, the end of second adjustment mechanism206 engages second coupling member 214 to maintain second portion 42 inits pivoted position relative to guide member 200. Second adjustmentmechanism 206 can also be manipulated by the surgeon to make adjustmentsin the pivotal position of second portion 42 relative to guide member200 and first portion 22.

Referring now to FIG. 14, there is shown another embodiment instrument220 for separating first and second portions 22, 42 of retractor 20.Instrument 220 includes a first handle 222 pivotally coupled to a secondhandle 224 about pin 226. First handle 222 includes a distal portion 223having a coupling member 228. Coupling member 228 includes a slot 230for receiving engagement member 32 of first portion 22 therein. Secondhandle 224 includes a distal portion 225 having a coupling member 232.Coupling member 232 includes a slot 234 for receiving engagement member52 of second portion 42 therein. A locking member 236 is pivotallycoupled at one end to first handle 222, and extends through slot 238 ofsecond handle 224 for releasable locking engagement therewith.

In use, instrument 220 is mounted on retractor 20 with coupling members228, 232 in engagement with respective ones of engagement members 32,52. Handles 222, 224 are moved toward one another in the directionindicated by arrows 240, 242 to move coupling members 228, 232 away fromone another. In turn, first portion 22 and second portion 42 areseparated from one another.

Retractor 20 can be adapted to guide first and second portions 22, 42during separation and to maintain the separation provided withinstrument 220. In the illustrated embodiment, collar 28 of firstportion 22 includes opposite first and second ears 240, 242 extendingbeyond the adjacent edges 25 toward second portion 42. Second portion 42includes first guide member 246 positionable over first ear 240, andsecond guide member 250 positionable over second ear 242. First guidemember 246 includes a slot 248 and second guide member 250 includes aslot 252. A first cam locking mechanism 254 extends through slot 248 andcouples first ear 240 to first guide member 248. A second cam lockingmechanism 256 extends through slot 252 and couples second ear 242 tosecond guide member 250.

First cam locking mechanism 254 includes a lever 258 that clamps alocking body 260 against first ear 240 and first guide member 246, asshown in FIG. 14. Similarly, second cam locking mechanism 256 includes alever 262 that clamps a locking body 264 against second ear 242 andsecond guide member 250, as shown in FIG. 14. When it is desired to movefirst portion 22 and/or second portion 42, levers 258 and 262 arerotated to release the respective clamped locking body 260, 264,respectively. Instrument 220 can then be used to apply a separationforce, or first and second portions 22, 42 can be moved toward oneanother for easy removal from the incision.

It is contemplated that guide members 246, 250 can be curved or arcuateto follow the path of coupling members 228, 232 as coupling members 228,232 are separated with handles 222, 224. In this manner, first portion22 and second portion 42 are simultaneously pivoted/rotated andlaterally separated with instrument 220. It is further contemplated thatone or more guide members between first portion 22 and second portion 42could be configured to provide only a lateral separation path or only arotational separation path. Other embodiments contemplate guide memberswhich provide a combined rotational and lateral separation path.

It is contemplated that for spinal surgery various retractors 20 can beprovided in a kit with lengths ranging from 20 millimeters to 100millimeters in increments of 10 or 20 millimeters. It is furthercontemplated that retractor 20 can be provided in a kit with varioussized working insertion configurations, such as 14, 16, 18, 20, 21 or 25millimeters for initial insertion width 55. It should be understood,however, that the present invention contemplates that retractor 20 canhave other lengths and diameters and can be provided in a kit withdifferent increments. The appropriate length for retractor 20 willdepend on the depth of the desired surgical location below the skin ofthe patient, the anatomical location of the surgery, and the patient'sanatomy. These factors in retractor selection can be evaluated throughpre-operative planning prior to surgery by x-rays or other known imagingtechnique, and can be adjusted during the surgical procedure ifnecessary since retractors of differing lengths and working channelsizes can be made available.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, and that all changes andmodifications that come within the spirit of the invention are desiredto be protected.

1. A system for retracting tissue in a patient, comprising: a retractorincluding: a first portion having a proximal end and a distal end; asecond portion having a proximal end and a distal end, said secondportion forming with said first portion a working channel incommunication with an exterior of said first and second portions at saidproximal ends and said distal ends with said working channel beingenclosed between said proximal and distal ends by said first portionbeing positioned in overlapping relation to said second portion alongsaid working channel from said distal end toward said proximal end,wherein said working channel is enlargeable by laterally moving each ofsaid first and second portions away from one another to position saidfirst and second retractor portions in non-overlapping relation to forma space that opens said working channel said between first and secondretractor portions at least from said proximal end toward said distalend and pivoting each of said distal ends of said first and secondportions away from one another; and a sequential dilation instrumentcomprising at least two tissue dilators positionable one over the otherto enlarge an opening in the tissue of the patient, said working channelof said retractor being sized for positioning about a last inserted oneof said at least two tissue dilators.
 2. The system of claim 1, whereinonly a portion of said working channel is enclosed by said first andsecond portions when said working channel is enlarged.
 3. The system ofclaim 1, wherein each of said first and second portions includes asemi-cylindrical body.
 4. The system of claim 1, wherein: said firstportion includes opposite edges extending therealong between saidproximal end and said distal end thereof; said second portion includesopposite edges extending therealong between said proximal end and saiddistal end thereof; when said working channel is enclosed said oppositeedges of said first portion interdigitate with adjacent respective onesof said opposite edges of said second portion; and when said workingchannel is enlarged said opposite edges of said first portion areseparated from respective ones of said opposite edges of said secondportion.
 5. The system of claim 4, wherein said opposite edges of saidfirst portion include an outer recess extending therealong and saidopposite edges of said second portion include an inner recess therealongso that said opposite edges of said first portion and said oppositeedges of said second portion abut one another in said recesses when saidworking channel is substantially enclosed by said first and secondportions.
 6. The system of claim 1, wherein said working channel definesa generally circular cross-section when enclosed by said first andsecond portions and a generally oval cross-section when said first andsecond portions are separated.
 7. The system of claim 1, wherein said atleast two tissue dilators includes three or more tissue dilators.
 8. Asystem for retracting tissue in a patient, comprising: a first portionand a second portion adjacent said first portion; a working channelbetween said first and second portions sized to receive at least onesurgical instrument for performance of a surgical procedure; and saidworking channel having an insertion configuration wherein said workingchannel defines a cross-section circumscribed by said first and secondportions overlapping one another along substantially an entire length ofsaid first and second portions and an enlarged configuration whereineach of said first and said portions are laterally separable andpivotable relative to one another to provide said working channel with across-section at least partially circumscribed by each of said first andsecond portions and tissue of the patient between said first and secondportions when said working channel is enlarged in the patient, whereinin said enlarged configuration said first and second portions arepositioned in non-overlapping configuration to form a space between saidfirst and second portions that opens said working channel along saidfirst and second portions from said proximal ends to said distal ends.9. The system of claim 8, wherein said first and second portions eachinclude a length between a distal end and a proximal end thereof suchthat said proximal ends are positionable outside the patient and saiddistal ends are positionable in the patient.
 10. The system of claim 8,wherein said cross-section of said working channel is circular in saidinsertion configuration and said cross-section of said working channelis oval in said enlarged configuration.
 11. The system of claim 8,wherein said first portion includes opposite edges extending betweensaid distal and proximal ends thereof, said second portion includesopposite edges extending between said distal and proximal ends thereofabutting said edges of said first portion with said working channel insaid insertion configuration.
 12. The system of claim 8, wherein: saidfirst portion includes opposite edges extending therealong between saidproximal end and said distal end thereof; said second portion includesopposite edges extending therealong between said proximal end and saiddistal end thereof; when said working channel is in said insertionconfiguration said opposite edges of said first portion are adjacent toand interdigitate with respective ones of said opposite edges of saidsecond portion; and when said working channel is in said enlargedconfiguration said opposite edges of said first portion are separatedfrom respective ones of said opposite edges of said second portion. 13.The system of claim 8, wherein each of said first and second portionsincludes a body with a semi-circular cross-section.
 14. The system ofclaim 8, further comprising a sequential dilation instrument comprisingat least two tissue dilators positionable one over the other to enlargean opening in the tissue of the patient, said working channel of saidretractor being sized for positioning about a last inserted one of saidat least two dilators when in said insertion configuration.
 15. A systemfor retracting tissue in a patient, comprising: a retractor including: afirst portion and a second portion each having a proximal end and adistal end, said first and second portions overlapping one another fromsaid distal end toward said proximal end and enclosing a working channelin an insertion configuration that extends between and opens at each ofsaid distal and proximal ends, wherein said working channel isenlargeable by laterally moving and pivoting each of said first andsecond portions away from one another to separate said first and secondportions from said overlapping arrangement in said insertionconfiguration to a non-overlapping configuration and open said workingchannel along said first and second portions by forming a space betweensaid first and second portions from said proximal ends to said distalends of said first and second portion; and a sequential dilationinstrument comprising at least two tissue dilators positionable one overthe other to enlarge an opening in the tissue of the patient, saidworking channel of said retractor being sized for positioning inclose-fitting relation about a last inserted one of said at least twotissue dilators.
 16. The system of claim 15, wherein said workingchannel has a generally circular cross-section in said insertionconfiguration and a generally oval cross-section when enlarged.
 17. Thesystem of claim 15, wherein said at least two tissue dilators includesthree or more tissue dilators.
 18. The system of claim 15, wherein onlya portion of said working channel is enclosed by said first and secondportions when said working channel is enlarged.
 19. The system of claim15, wherein said first and second portions each include a length betweena distal end and a proximal end thereof such that said proximal ends arepositionable outside the patient and said distal ends are positionablein the patient.
 20. The system of claim 15, wherein said first portionincludes opposite edges extending between said distal and proximal endsthereof, said second portion includes opposite edges extending betweensaid distal and proximal ends thereof interdigitating with said edges ofsaid first portion with said working channel in said insertionconfiguration.
 21. The system of claim 15, wherein: said first portionincludes opposite edges extending therealong between said proximal endand said distal end thereof, at least one of said opposite edges of saidfirst portion including an outer recess extending therealong; and saidsecond portion includes opposite edges extending therealong between saidproximal end and said distal end thereof, at least one of said oppositeedges of said second portion including an inner recess extendingtherealong, wherein said at least one opposite edge of said firstportion and said at least one opposite edge of said second portion abutone another in said recesses when said working channel is substantiallyenclosed by said first and second portions and when said working channelis enlarged said at least one opposite edge of said first portion isseparated from said at least one opposite edge of said second portion.22. The system of claim 8, wherein: said first portion includes oppositeedges extending therealong between said proximal end and said distal endthereof, at least one of said opposite edges of said first portionincluding an outer recess extending therealong; and said second portionincludes opposite edges extending therealong between said proximal endand said distal end thereof, at least one of said opposite edges of saidsecond portion including an inner recess extending therealong, whereinsaid at least one opposite edge of said first portion and said at leastone opposite edge of said second portion abut one another in saidrecesses when said working channel is substantially enclosed by saidfirst and second portions and when said working channel is enlarged saidat least one opposite edge of said first portion is separated from saidat least one opposite edge of said second portion.